, No. 3 March 1996

: 1 c*,$ 'G : in Animals lj*d Is .-*,; b.1 tJ

-71, W

-'The primary goal in dealing with i I ., pressure wounds is preventing

them through padding, skin Auburn University . . *, .--P+J university of Georgia $.I,-*

inspection, appropriate skin Steven F. Swaim, DVM, MS - , oan R. Coates, DVM, M S '

R. Reid Hanson, Jr., DVM hygiene, changes in position, >,

adequate nutrition, and special --.I

bandages and splints.

P ressure wounds occur in dogs, cats, and hArses. In small animals, pressure wounds are more common in dogs; however, a particularly severe form of pressure wound in cats occurs following onychectomy when paw ban-

dages are placed too tightly. Various terms will be used in this article to de-

Animal care personnel are often i unaware of developing decubital I ulcers because an animal's I haircoat conceals the signs of 1 this pressure wound, p. 206. I

--m Decubjtal ulcers begin from pressure-induced tissue 'kchernia which leads to necrosis and bioch~emical changes in the skin that contribute to pathologic changes (i.e., oxygen free radicals and thromboxane AJ, p. 205.

4 Pressure wounds are treated by surgery, topical medications, bandages, and most importantly, by prevention of further pressure, p. 209.

-4 Horses that have been recumbent fur long periods (such as occurs with postanesthetic myopathies, neurologic disease, limb fractures, and laminitis) are prone to decubital lesions,

I scribe the-types of dermal pressure wounds. In general, however, a pressure wound is a wound induced by any form of pressure on the skin. Pressure wounds encompass decubital ulcers, which are caused by prolonged recumben- cy and the resultant pressure on skin that is trapped between the surface on which the animal is resting and a bony prominence. : 1~

PRESSURE WOUNDS I N SMALL ANIMALS Causes

I

Decubital ulcers are a problem in dogs.'" Prevention plays a major role in dealing with decubital ulcers; however, once they develop, treatment becomes necessary. Certain breeds of dogs are predisposed to decubital ulcers because of a neurologic condition associated with the breed. Two common examples of such neurologic conditions are presented, but it should be noted that any neu- rologic condition resulting in paraplegia or tetraplegia can predispose to decu- bital .ulcers. Following surgical procedures to treat these conditions, decubital ulcers are common if preventive measures are not taken.'

Breeds of dogs that are predisposed to intervertebral disk herniation (e.g., dachshunds) are more prone than other breeds to paraplegia and tetraplegia, which can result in decubital ulcers. Large- and giant-breed dogs (e.g., Dober- man pinschers and Great Danes) are predisposed to the cervical vertebral insta- bility/malformation syndrome. The syndrome may require surgery, which may be associated with the development of decubital ulcers secondary to temporary tetraplegia.

Pressure wounds may result from damage to peripheral nerves. An example is trauma to a forelimb with damage to the ulnar nerve and a resulting motor nerve deficit in the flexor muscles of the forelimb. The abnormal weight distri- bution on the paw as a result of this deficit may lead to an ulcer at the proxi-

1 molateral aspect of the metacarpal paw 8 ' , ' ' .

, A

,edisposin 2 decreasc Its from c

11a of humen tibia

1. ischlatic tuberosity 2. greater tmchanter 3. tuber coxae 4. acromion of SCapL 5. lateral epicondyle 6. lateral condyle of 7. laleral malleolus 8. sides of fifth dl( 9. olecranon

10. calcaneal tuber 11. sternum

Decubital ulcers are also associated with orthopedic abnormalities in dogsa De- cubital ulcers may occur sec- ondary to the paraplegia or tetraplegia associated with spinal trauma. Animals that are immobile because of mul- tiple long bone andlor pelvic fractures are also subject to decubital ulcers. Related to orthopedic conditions that cause decubital ulcers are the pressure wounds that develop over bony prominences as a result of an improperly ap- plied or padded coaptation cast or ~pl int . ' .~ . '~ ." These wounds are usually the result of light pressure over a pro- longed period.' Another more severe form of bandage- Figure 1-Areas over bony prominences are prone to decubital ulcers. (From Swaim SF, or cast-induced pressure Henderson RA: Small Animal Wound Management. Philadelphia, Lea & Febiger, 1990, p wound occurs when ban- 78. Reproduced with permission.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . dages or casts are applied too tightly. The result is circulatory insufficiency of the paw wound dehiscence may lead to a chronic, nonhealing and sloughing5 This is an unfortunate occurrence with ulcer if proper preventive measures are not taken and tight bandaging after onychectomy in cats. the animal continues to lie in sternal recumbency and

When a debilitated dog or one that is convalescing place pressure over the surgical site.I4 Hygromas may from severe injury or illness is unable or unwilling to form abscesses that rupture, which results in a chronic change body position, decubital ulcers are likely to de- open wound or ulcer over the olecranon. velop. Pr g factors to these decubital ulcers in- Hip dysplasia may predispose large dogs to elbow hy- clude thc : in padding between skin and bone groma. Because of the pain associated with the condi- that resu lisease, atrophy, or loss of adipose tis- tion, the dog may be less able to protect the elbow from sue; loss of tissue elasticity; malnutrition (associated trauma when lying down.5 Specifically, the pain, which with hypoproteinemia, anemia, or vitamin deficien- is in the coxofemoral joint, becomes so great that the cies); skin maceration; soft tissue contusion; skin chaf- dog drops on the olecranons rather than easing onto ing; skin friction and stretching; skin irritation from them when lying down in sternal recumbency. Thus, urine and feces; skin burns and scalds; and improper skin over the elbow is traumatized and an elbow hygro- nursing care.M ma may start to develop, which could lead to ulceration

Greyhounds have a very angular conformation, short problems. hair, and thin skin. These characteristics predispose to the development of decubital ulcer^.^.^^^^^ Location and Pathogenesis

Elbow hygroma is another condition that can result Decubital ulcers in dogs develop over bony promi- from dermal pressure and can lead to another form of nences5 (Figure 1). Most of the decubital ulcer sites are pressure wound-an elbow ulcer. Elbow hygromas usu- on the lateral aspect of the dog because recumbent ally develop secondary to repeated pressure or trauma dogs usually lie in lateral recumbency. Because of their over the olecranon in young large- or giant-breed dogs greater weight, large dogs are more prone to develop (e.g., German shepherds, Great Danes, bull mastiffs, decubital ulcers, especially over the greater trochanter and Irish w o l f h ~ u n d s ) . l ~ ~ ~ ~ The condition is often asso- (Figure 2). Small, paraplegic dogs that tend to sit up ciated with lying in sternal recumbency on unpadded on the perineal region for prolonged periods tend to surfaces, which places pressure on skin over the olecra- develop decubital ulcers over the ischiatic tuberosities3 nons. After surgical excision of an elbow hygroma, (Figure 3).

T h e primary pathologic - Preventive Measures change of decubital ulcers is T h e primary goal with tissue ischemia and the re- decubital ulcers is preven- sultant necrosis as soft tis- tion. Numerous measures sues are compressed benveen are available to accomplish a bony prominence and the this goal. surface on which the animal Padding. Padded bed- is resting. With improperly ding is a primary means of applied casts or bandages, preventing decubital ulcers. the cast or splint material Blankets, coated or closed- causes t h e compress ion. cell foam pads, air mattress- Pressure on the soft tissues - - - es, water mattresses, thick associated with a developing Figure 2 - ~ ~ ~ ~ b i ~ ~ l ulcer over grearer rrochanrt .an straw bedding, sheepskin decubital ulcer causes focal ~ ~ i ~ h serter. pads, and artificial fleece intravaScular changes, which - - - - - ----------------- - - - - - - - - - - - - - - - - - - - - - pads have been described as - result in vascular occlusion means for p rov id ing a and tissue ischemia. The de = padded surface." Sheep- gree and severity of ulcera- r ;* C . + , *k,i skin pads and foam rubber tion vary with the extent of c: i-. - '. mattresses he lp provide vascular occlusion."jBio- some air circulation under chemical changes occur the animal and help con- wi th in the ischemic skin duct moisture (i.e., urine) and contribute to necrosis. away from the skin. Placing It has been theorized that these pads and mattresses on damage to the compressed grates o r racks also helps skin also occurs d u r i n g separate the animal f rom reperfusion with reoxygena- Foam rubber with tion of ischemic tissue after a convoluted, egg-crate de- Pressure is released. The en- Figure 3-DecuLILdl ulcer over [he ischial tuberosity of a sign provides a good bed- dothelium of vessels is dam- poodle. ding surface. aged by oxygen free ----.-----"I -------- I- ----*- - --------- ------,-.-- In an evaluation of dogs

Thromboxane B,, a mea- with severe paraparesis or surable stable metabolite of thromboxane A,, has been paraplegia resulting from thoracolumbar spinal trauma, identified in tissue of naturally occurring decubital ul- it was found that these dogs assumed the posture asso- cers and impending decubital ulcers in greyhounds.12 In ciated with the Schiff-Sherrington syndrome with addition, in greyhounds, this pathobiochemical has also pelvic limb spasticiry. The result of this neurologic sta- been identified in developing dermal pressure lesions. tus was that some dogs maintained a posture in which These lesions were induced over bony prominences by weight was distributed o n the ischiatic tuberosities, application of coaptation casts with only stockinette thus predisposing the area to decubital ulcer develop- l ining and n o padding."," Thromboxane A? con- ment. Vinyl-covered, convoluted foam rubber pads tributes to the existing dermal ischemia by causing ( C o r n y Dog Bed, J & M Stuart Co, Inc, St. Louis, vasoconstriction and inducing intravascular platelet ag- MO) have been found to be very effective in helping to gregation. T h e platelet aggregation leads to vascular prevent decubital ulcers over the ischiatic t ~ b e r o s i t i e s . ~ ~ thrombosis, which restricts vascular flow to the tissues An artificial fleece (Unreal Lamb SkinB, Alpha Protech, and causes progressive dermal ischemia.'' Research in- North Salt Lake, UT) placed over vinyl-covered foam dicates this chemically induced process is a factor in the rubber pads has also been found to be effective in help- pathogenesis of dermal pressure lesions. Systemic ad- ing prevent decubital ulcers in dogs. The fleece pro- ministration of a thromboxane antagonist in a grey- vides an additional dry and soft surface to the bedding. hound model for dermal pressure lesions resulted in re- Proper padding of coaptation casts is important for duced thromboxane tissue levels, fewer physical dermal the prevention of pressure lesions over bony promi- abnormalities, and less severe histopathologic changes nences. Evaluation of the dermal effects of different in the pressure-exposed skin of treated dogs than the configurations of cast padding in coaptation casts on pressure-exposed skin of untreated dogs indicated that absence of cast padding can cause

- The Compendium March 1 9 9 4

dermal pressure injury over - sharp prominences. In somc areas, localized cast padding may settle around larger prominences and increase pressure to potentiate der- mal pressure injury. Al- though pressure over bony can be used to resulct prominences may be signifi- cant immediately after ap- plying full-length cast padding and a coaptation cast, some compacting of the padding takes place. Figure 4-A donutshaped bandage made from a taped and the dog are placed thr

This provides the best fo'-m of cast padding to prevent dermal pressure injury."

Inspection. Veterinarians and veterinary technicians ------------------ ----------- --'-*-"'-"--- , way of keeping press have a challenge in dealing the skin overlying th with decubital ulcers because their patients are hirsute. mion of the scapula, tuber coxae, and greater troc Thus, the haircoat will conceal skin with an impending in large dogs. For ~ a r a ~ l e g i c or paraparetic decubital ulcer. It is import nel to part the hair over bon the underlying skin to ident and easily epilated hair.'.%

Some animals naturally tend to lick or chew at a ban- dage or cast. In other ani chewing may indicate an un the result of an ill-fitting cas stances, it is wise to remove the cast - - or bandage and check for pressure wounds. In addition, a cast that has an offensive odor or an internally derived stain over a bony promi- nence should be removed and the tissues checked for pressure wounds.

Positioning. The body position of an animal that is unable or unwill- ing to change its own position should be changed frequently to help prevent decubital ulcers.'" Ide- ally, position should be changed ev- ery 2 hours1"; however, a range of 1

. . to 5 hours has been de~cribed.~ Posi- tions should alternate between left lateral, sternal, and right lateral.'s3 When placed in sternal recumbency, positioning the pelvic limbs caudally in extension behind the dog helps prevent joint contraction problems.' Some dogs that are able to move have a preferred position; this posi-

I

I Predisposing Factors to Pressure Wounds I Brecd-assoe:iatecI nemoiogic conditions that result in paraplegia

tetraplegia, such as intervertebral disln herniation in dachshu~ds , and the cervical vertebral instabiIiryZmalhrmation syndrome in, Doberman pinschers, Great Danes, a d other large- or giant-brc dogs Any neurologic eonditian that results in paraplegia or temp including the O&P& and neurologic abnormalities assoc with spinal frmures Damage to peripheral nerves that results in abnormal limb or posirion and weight-kari i I Immobility resulting h m multiple long-bone andlor pelvic

''

fractures ,::! I Improperly applied or padded maptation casts or splints

;t - H The inabiliq or unwillingness of a debilitated or convalescing ,i?+

animal to change body position ..id : 5

Breed-asxhted dnractwisticx, such as the angular conf~rmatio@~$ short hair, afrd thin skin of greyhounds : - ,y t ..< -

A+., I The presence of hygmmas, which can l ad to elbow ulcers . --

- cilitates cleaning in the pres- on the limbs (e.gs, mer-&gg ence of fecal in~ontinence.~ Proper maintenance of a dosed collection system can help prevent urine scalding and skin maceration in ani- mals with urinary inconti- nence.' Whirlpool or warm- water baths, two to three times daily, help keep the skin clean and promote cir- ~ulation.~ When a decubital ulcer is developing or has de- veloped on the skin over the a ischiatic tuberosities, fecal contamination can enhance I wound development or slow healing. A piece of rubber sheeting (cut from a surgery glove) sutured across the perineal area under the anus can help prevent fecal con- tamination of the area.

NwwZtisn. Animals re- quire proper nutrition as part of the preventive rou- tine for decubital ulcers." A

I the olecranon area is 4

pipe insulation of the -a

I large enough to acco date the olecranon is the center of each pi split foam rubber 5A). The pieces are

Flgun 5B extension, the cranial plements has hen advocat- Figure +(A) Foam rubber pipe insulation split face of the joint is I ed." with a hole cut in the center to fit over an impending de- padded with cas

r a repair site. (B) Two and the

d Managmrnt. with the hole over the

- - I IIIlaUbIYIua, - - CV%Cl, I ,,", ,, , ,,. .kproduced with cranon. The paddin I pressure off skin ove; a bony ,,issio,.~ foam rubber pad are prominence. such pressure :------------------------------------.-------- in place (Figure 5B), can be the result of a partic- prevents joint flexion. ular posture that an animal has assumed. the dog cannot assume a position of stern

A donut-shaped bandage can be placed over a bony cy, which in turn, prevents the dog from prominence on the lateral aspect of a limb (i.e., lateral sure on the olecranon area. In obese dogs malleolus) to keep pressure off the skin. Such a bandage humeral area, a spica-type bandage is sometimes

form the shape of a don;;. he ban&e is tapedio the of the elbow bk&e bridges the ;adiohumeral jarl limb, with the donut hole over the lesion5 (Figure 4). thereby preventing the dog from bending the elbokar; This type of bandage, although not advocated in ueat- ing in sternal recumbency, and putting pressure cm r ing decubital ulcers in humans, has been used to keep elbow (Figure 6). pressure off decubital ulcers and decubital ulcer repair In small, paraplegic dogs that tend to sit on sites on the lower limbs of dogs. ineal area, decubital ulcers over the ischiatic tub

Donut-shaped bandages are difficult to hold in place can be prevented by placing side splints along t d around decubital ulcers over bony prominences higher of the dog such that the splints extend beyond the pexd

ineal area (Figure 7). These extended side splints pre- vent the dog from attaining a posture that allows contact between the ischiatic area and the surface on which the dog is resting."

General Wound Management

Decubital ulcers in ani- mals are classified in severity from gade I to IV (Table I) and treatment is based on these gades. The appear- ance of the various grades of ulcers is shown in Figure 8. A major part of treating de- cubital ulcers is relieving the pressure over the ulcer. Therefore, many of the fac- tors presented as preventive measures also apply in the therapy of decubital ulcers. Wound debridement, stim- ulation of healthy granula- tion tissue and wound con- traction, and surgical wound closure are the wound man- agement principles used in treating decubital ulcers. The following discussion presents a general treatment regimen for managing decu- bital ulcers in dogs.5

Grade I ulcers are treated by periodic wound cleans- ing and removal of slough- ing surface tissue. T h e wound is allowed to heal by second intention.

With grade I1 ulcers, surgi- cal and/or bandage debride- ment is done to cleanse the wound and free it of necrotic tissue. Wet-to-dry bandages are used. Once a healthy bed of granulation tissue has formed, the wound is al- lowed to heal by second in- tention or is closed by sec- ondary closure. If secondary ( made to keep suture Lines away

Figure +An aluminum rod loop splint that is incorporat- ed in the front of an elbow bandage prevents elbow flex- ion, thereby keeping pressure off the olecranon area. , - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+*- :

. . ' . . . . # h ~ . '. rect an elbow pressure ulcer in an Irish w ~ l f h o u n d . ~ ~ A similar potential flap that could add bulk over the ole- cranon area is a myocuta- neous flap containing the latissimus dorsi muscle transposed off the side of the dog.*' Muscle flaps from the cranial sartorius and rec- tus femoris muscles have been used successfully to treat decubital ulcers over

Figure I-rleces or aluminum sp~lnc Incorporatea In a the greater trochanter in body bandage to extend beyond the perineal area. The dogs.13 A neurovascular is- splints keep the ischial tuberosities from contacting the land pedicle flap from the surface on which the animal is resting. dorsal metacarpus has been ----------------------------------------------

described for repair of ulcers losure is used, efforts are at the proximolateral aspect of the metacarpal pad re- from bony prominences. sulting from ulnar nerve dama e.*.'

. : .,.:.Weritiw' ./'..': . . : . - . - . 'T~~s% .. . . (continuer on page 212)

Grade I11 ulcers with un- dermining of surrounding tissue are debrided of nonvi- able tissue and treated as open wounds until a healthy bed of granulation tissue is present. Either wet-to-dry or dry-to-dry bandages are used. When pockets are present in the undermined skin, a Penrose drain that is !4 inch in diameter is placed at the most dependent area. Secondary closure is per- formed after a healthy bed of granulation tissue has formed.

With grade IV ulcers, in- fected tissue (including any infected bone) is removed. Sinus tracts and pockets are excised or opened and de- brided. Guidelines for grade I11 ulcer bandaging, drain placement, and secondary closure are then followed.

Because of the size and/or location of some ulcers, a local skin flap may be neces- sary for closure (Figure 9). An axial pattern skin flap based on the thoracodorsal vessels has been used to cor-

Ulcer

Grade

Grade

Grade

. .-... Manag produc

ification o f Decubiti

Charactei

Dark re blanch upper d

:ddened ax on pressur lermis ma!

,ea that do .e; epidern lr slough

es not lis and

Full-thi the sub1

Ulcer e subcuta deeper : LA .. ..A'

Ulcer e Fascia d' osteom may be

Lea & Febl

n loss don tissue

ough the c hone:

o the may

leep

tptic arthr

., , .

Numerous topical medica- TABLE I nents of such a preparation tions can be used in the may provide nutrients for treatment of decubital ulcers. wound tissue to promote The following are medica- healing2' Maltodextrin has tions primarily used at the potential for treating other Auburn University, College types of special wounds; of Veterinary Medicine, De- however, research on such partment of Small Animal applications is indicated. Surgery and Medicine. After ckness ski Contact (primary) ban- surgical and/or bandage de- cutaneous dage materials used with bridement of a wound, the wet-to-dry and dry-to-dry goal is to control infection tends through the bandages in early decubital and stimulate the develop- neous tissue down t ulcer therapy are adherent ment of a healthy bed of fascia; wound edges gauze sponges. Once de- granulation tissue in the ul- :rmined brided, wounds are covered cer. Topical antibiotics help with a nonadherent ban- control local infection, and tends thrl dage, such as a Telfa Pad after a healthy bed of granu-

own to thc -----, yelitis or st

(KenVet, Ashland, O H ) , lation tissue is present, an- present RELEASE Non-Adhering tibiotics may help control Dressing (Johnson & John- surface bacteria. The granu- >,,,, >*, ne=derson RA: Small Anrmal Wound son P T O ~ U C ~ S , Inc., New lation tissue, however, serves rment. Philadelphia, I iger, 1990, Brunswick, NJ), or Hydra- as a barrier to control against .ed with permission. sorb sponge (KenVet, Ash- deeper infection. If deeper land, OH). These bandages tissue infection is a factor, systemic antibiotics should be are used in combination with the previously described administered. The choice of antibiotic is based on cul- medications. ture and sensitivity test results.

Topical medications are used to help stimulate the PRESSURE WOUNDS IN LARGE ANIMALS formation of !granulation tissue in wounds. One vulner- Causes and Pathogenesis ary compound (Granulexa, Pfizer Animal Health, West Horses that are recumbent for long periods, particu- Chester, PA) contains trypsin as an enzymatic debrid- larly those with postanesthetic myopathies, neurologic ing agent and balsam of Peru as an angiogenesis stimu- disease, limb fractures, or laminitis, are most prone to lant. A hydrogel topical dressing that contains aloe Vera develop decubital ulcers (Figure 10). In horses, as in gel extract with acemannan (Carravet' [CVMD], Car- other species, decubital lesions usually occur as a result rington Laboratories, Inc., Irving, TX) has also been of prolonged application of pressure in a relatively used to stimulate granulation tissue formation. Ace- small area of the body; tissue ischemia and necrosis mannan is a macrophage stimulant, which enhances then o c c ~ r . ~ ~ . ~ ' Decubital ulcers are particularly serious the production of the cytokines interleukin-1 and tu- near a joint, because infection of the synovial spaces mor necrosis These two cytokines, in turn, can result.30 Preexisting conditions that accelerate the stimulate angiogenesis in wounds.25 onset of decubital ulcers in horses include some of the

Hydrophilic agents pull body fluids through the same conditions associated with decubital ulcers in wound tissues to bathe them from the inside and en- dogs-loss of subcutaneous padding as a result of dis- hance healing. A dry starch copolymer flake dressing ease, malnutrition, skin friction, urinary and fecal in- (Avalon Copolymer Flakes', Summit Hill Laboratories, continence, inadequate nursing care, or poor skin hy- Navesink, NJ) and a hydrophilic dextran polymer giene.29 (DEBRISANa, Johnson & Johnson Products, Inc., Although no detailed pathologic or pathobiochemi- New Brunswick, NJ) have been used in the past for this cal studies have been reported for pressure lesion patho- purpose.26 The copolymer flake dressing is still avail- genesis in large animals, it is reasonable to assume that able; however, the dextran polymer is no longer avail- the pathologic changes in large animals would be simi- able. A hydrophilic powder containing D-glucose lar to those occurring in tissues of other species. The le- polysaccharide, maltodextrin N.F. (Intracell", Techni- sions initially have an erythematous to reddish-purple Vet, Inc., Amarillo, TX), has been used to cleanse and discoloration. This progresses to oozing, necrosis, and promote healing. It has been proposed that the compo- ulceration. The resultant ulcers tend to be deep, under-

- mnpnrlirrm March 1996 Small Animal 213

- I . ( I

J

A Q

;$ +&

.fl 7 1 .

., L %

epidermis

\ -

dermis -

subcutaneOu5- fat

deep musck/ fa-' /-" r I"P

7 bone , , J 3 5 r I ?. I l ! ,?>a>

Grade I-Dark reddened area with involvement

c Grade ll-Ulcer extends to the subcutaneous

of the epidermis and upper dermis tieeue

I 1

t 4 I

3 -!

7 \W' .' e - I astjst.l I d \ rn I - , , )'. - ; ,

Grade Ill-Ulcer extends through the subcutaneous Grade IV-Ulcer extends to bone; osteomyeiitis tissue to deeper fascia; the wound edges or septic arthritis may be present may be undermined

-ew%

d %5

I

9

4 4 ! 4

j ." ::

3 4 4

7 * u

Fiuure &-Grades of decubital ulcers. ------------------------------------------------------------------------------------------------ mined at the edges, secondarily infected, and very slow though not classified as true pressure wounds, the sores to heaL3' create full-thickness skin lesions that can have devastat-

Casting of limbs in large animals coupled with a sig- ing results if not properly treated. To reduce the possi- 1 nificant amount of movement by the animal may result bility of friction sores, the fiberglass casting material

in friction sores underneath the casting material. Al- must conform to the limb as perfectly as possible. Ex- ,

- . m..q,&t-~.;-m;:;~;;.: ,.., >-,~ ~. ?..

iLLJ ,.z,T.c-. ~-~g:f, : t; FRICTION SORE -

BERGLASS CASTING MATERIAL

PHow to Prevent Pressure Wounds Provide dean and dry padded bedding

1 Use proper padding for coaptadon casts ? I Carefully inspect the haircoat; part the hair over bony prominences

and observe the underlying skin Apply cats or bandages carefully, if the atlimal is licking or chewing the cast or bandage, remove it to check for pressure lesions ' d Remove casts or bandages that have an o&mive odor or an internally derived stain over a bony prominence and check for

I pressure lesions

i Frequently change the body position of an animal that is unable or unwilling to change its position as well as the position of an animal that is not totally immobile LNL that has a preferred position,

L which predisposes to decubital dws Use slings, if necessary, to suppoix dogs and horses in a sanding position for several hours daily

I Keep the animal's skin dean and dry (i.e., free of urine and feces) Provide proper nutrition

m Be creative about bandages and splinting so that pressure is kept off skin aver bony prominences and so that the animal cannot assume a posture that would place pressure on skin over a bony prominence

8 Provide proper positioning, padding, and limb support for large animals during anesthmia

symptomatic treatment. The gener- alized myositis associated with hy- potension, however, may be so se- vere that the horse is not able to stand and ultimately requires eu- thanasia. Such horses are in extreme pain and require aggressive support- ive therapy. "

Preventive Measures During anesthesia, careful atten-

tion to patient positioning, padding, and limb support is critical for the - - prevention of postoperative neu- ropathy and my~sit is . '~ Facial, radi- al, and peroneal nerve paresis may be produced by even short periods of lateral recumbency on hard sur- faces. If the horse is in lateral recum- bency, the undersurface of the ani- mal (especially the shoulder and hip) should be padded. Inner tubes, air mattresses, dunnage bags, or foam padd ing ( 1 5 t o 20 c m in thickness) have been used. T h e down limbs should be pulled for-

cessive padding compresses inside the cast, leading to increased move- ment of the l imb with resultant friction sores.

One of the first signs that a cast is not fitting properly is reluctance

cast, moisture of the cast, or any foul odor emanating from above or Figure 9A Figure 9B

the cast area indicates that Figure 9-(A) Debridement of wound edges of a decubital ulcer over the lateral the cast should be removed, the humeral epicondyle area and skin for creating a transposition flap (F) for surgical

repair. (B) Transposition flap (F) covering the ulcer. limb evaluated* 2nd a new cast ap- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - , & * - - - - - - - , - - - - - -

plied. Skin necrosis or wound de- hiscence can progress to the point where the damage ward to protect major nerves. Halters should be re- created by the cast is worse than the original lesion that moved to prevent facial nerve paralysis. The up limbs led to the application of the ~ a s t . ' ~ , ~ ' should be supported to prevent undue compression of

Postanesthetic myopathies occur in horses in which and impaired blood flow to the large chest and thigh there is hypoperfusion during anesthetic recumbency. muscle masses. Unpadded ropes or tape should not be The hypoperfusion, which results from inappropriate used for positioning. In dorsal recumbency, the horse's positioning and inadequate padding, is particularly a back and neck should be padded and the legs should be problem in heavy-muscled breeds. When they are local, loosely extended to prevent compression and impaired myopathies and neuropathies usually resolve with blood flow due to limb flexion. Postoperative myositis

-- POSTANESTHETIC M Y O P A T H I E S ' O S I T I O N I N G I A D D I N ( I S U P P O R T

has been linked to hypoten- sion; therefore, the anes- thetist should monitor blood pressure closely to prevent hyp~tension.~'

Preventive measures should be instituted in any horse that remains recumbent for more than 3 hours. These measures include bandaging the lower extremities to pre- vent self-inflicted trauma and having clean, dry bed- ding free from e ~ c r e t a . ~ ~ , ~ ' The ~osition of a horse that is lying in lateral recumbency should be changed every 6 hours. It is preferable to maintain the horse in a ster- nal position to minimize pulmonary congestion and prolonged weight-bearing on skin surfaces over bony prominences. A body sling is useful to assist the horse to stand, thus decreasing mus- cle damage and the likeli- hood of decubital ulcer de- velopment. Slings may also improve a horse's attitude as well as increase limb use and ~irculat ion~ (Figure 1 1). The decision to use a sling should be made on an individual basis because some horses do not tolerate slings well.

Dr. Hanson has found that a bedding constructed with a 40-cm thickness of peat moss above a clay- based flooring works well in minimizing the incidence of decubital lesions. The peat

Figure.10-Extensive decubital ulceration in a horse recum- bent for a long period because of chronic laminitis. ---------------------------------------------*

Figure 11-A body sling assisting a horse to stand. -----------------------------------------*-*--

12- x 12-foot stall above a straw base, the horse will learn to lie on the side of the stall with the pillows. Although more expensive than peat moss, the use of pillows is a cleaner and equally effective method.

Treatment Severe myositis develops

rapidly in horses that are t o d - ly recumbent for more than 24 hours and that have not re- ceived proper care. To mini- . . mize the complications of re- cumbency and self-induced trauma, the previously de- scribed precautions should be employed as soon as possible to minimize hrther pressure to major muscles and other susceptible areas. Slinging should be attempted if feasi- ble.36 Skin sores or abrasions should be cleaned and lavaged twice daily with saline and an- tiseptic solutions to avoid sec- ondary infection^."*^^' Topi- cal antibiotic ointments, aluminum and magnesium hydroxide solutions (e.g., Maalox" [RhBne-Poulenc Rorer Pharmaceuticals Inc., Collegeville, PA]), emollient creams (e.g., Silvadenea cream [Hoechst Marion Rou&el Inc., Kansas City, MO]), otic cleaning solutions (e.g., Oti- Clens", [Pfizer Animal Health, West Chester, PA]), and granulated sugar have all been advocated to aid in heal-

moss reduces the shear Figure 12-Plastic-lined pillows used under a recumbent ing of decubital ulcers:0037 forces and friction to the horse to minimize decubital ulcer development. The pil- If spontaneous urination is skin. It also acts as a drying lows are placed on top of a straw bed. .- , not observed, the bladder agent by allowing excessive

- - - '- - - - - - - - - - -- - - - - - - - - - - - - - - -"--. t , a d , ,,. , should be manually expressed

moisture to be conducted per rectum or catheterized away from the skin. It is imperative that the top level of aseptically. An indwelling urinary catheter may be advis- the peat moss be changed frequently to prevent the able if prolonged recumbency is anticipated. Urine scald buildup of urine and feces. Plastic-covered pillows can should be prevented by application of petrolatum or 0th- also be used to minimize decubital ulcers (Figure 12). If er water-repellent ointments to areas likely to become wet approximately 40 pillows are placed on one side of a with urine.36 Prolonged use of oil-based ointments, how-

ever, may lead to maceration of the tissues. Adequate nutrition is necessary to promote healing of

decubital ulcers. A protein deficiency can cause general debilitation and increased susceptibility to tissue break- down. Severe anemia can result in low oxygenation of tis- sue and lead to the death of tissues subjected to pressure. Anorexia and inadequate food intake result in nutritional and caloric deficiencies that depress the healing pro- c e s ~ . ~ " ~ Mected horses should be fed a high-roughage, high-protein, and vitamin-supplemented diet.30.36.37

The most important aspect of therapy is to identify and correct the cause of the prolonged recumbency so the patient can stand. Surgical treatment of decubital ulcers is not as frequently performed in horses as it is in humans and small animals.30 Surgical debridement of infected granulation tissue, undermined and trauma- tized skin, and infected muscle and bone coupled with primary closure of the remaining skin defect has been used successfully. The use of skin flaps and grafts as well as myocutaneous flaps has not been specifically de- scribed for correcting equine decubital ulcers. If such procedures were used, it would first be necessary to cor- rect the condition that caused the recumbency and re- sultant ~lcer.~"kin grafts have been used to correct limb lesions resulting from improper casting.

Veterinarians, animal care personnel, and owners of- ten face the time- and money-consuming task of treat- ing pressure wounds. The primary objective for large animals, as for small animals, remains prevention.

4. Swaim SF, Angarano DW: Chronic problem wounds of dog limbs. Clin Dennatol8: 175-1 86, 1990.

5. Swaim SF, Henderson RA: Small Animal Wound Manage- ment. Philadelphia, Lea & Febiger, 1990, pp 52-86.

6. Swaim SF, Votau K: Prevention and treatment of decubital ulcers in the dog. VM SAC 65: 1069-1 074, 1975.

7. Knecht CD: Principles of neurosurgery, in Oliver JE, Hoer- lein BF, Mayhew IG (eds): Veterinary Neurology. Philadel- phia, WB Saunders Co, 1987, pp 408-415.

8. Gourley IM: Neurovascular island flap for treatment of trophic.metacarpal pad ulcer in the dog. JAAHA 14:119- 125, 1978.

9. Read RA: Probable trophic pad ulceration following trau- matic denervation: Reporr of two cases in dogs. Vet Surg 15:4044, 1986.

10. Holmberg DL: Tissue handling, in Whittick WG (ed): Ca- nine Orthopedics, ed 2. Philadelphia, Lea & Febiger, 1990, pp 146-1 57.

11. Swaim SF, Vaughn DM, Spalding PJ, et al: Evaluation of the dermal effect of cast padding in coaptation casts. Am J Vet Res 53:1266-1272, 1992.

12. Vaughn DM, Swaim SF, Milton JL: Evaluarion of throm- boxane in pressure wounds. Prostaglandins Leukot Essent Fany Acid 37:45-50, 1989.

13. Swaim SF, Bradley DM, Vaughn DM, ec al: The greyhound dog as a model for studying pressure ulcers. Decubim 6:32- 40, 1993.

14. Pope ER, Swairn SF: Chronic elbow ulceration repair utiliz- ing an axial pactern flap based on the thoracodorsal artery. JAAHA 22:89-93, 1986.

About the Authors Dr. Swaim is affiliated with the Scott-Ritchey Research ILUI8tRAnW for YOU, the

new Compendium Collection. sity, Aubum, Alabama. Dr. Hanson, who is a Diplomate of Topics include rhoracic, the American College of Veterinary Surgeons, is affiliated with the Department of Large Animal Surgery and Medicine of Auburn University. Dr. Coates, who is a radiology as well as radiation Diplomate of the American College of Veterinary lntemal biology, m, and

A M RM)lI ' and

REFERENCES . Bern CW: General nu* and client education, in Beta

T a B d e i l ~ : S e n d b o o l r t i r k , a n o y a , $ o n e ~ , d ~ a e m a& drsr to: MS lh&, 425 Phillips W #LBO, Trtnmn, MJ 08618-106-

lnchrdt ducWaedir ia&w cord no., cppCPPke duc, signuurr. M S 3 i h k $5Imul6i- '. Sherding RG (ads): Sambq M d of S d A n i d Aac- p l c W ~ d c r r O r ~ ~ . V I S A * , M P c u c u d . d ~ ~ l c o e p o s d

tkx. PhiladelphiaI WB Saunders Co, 19%. pp 330-335. 3. Parlecii MM: Adzr ofS+ &.a id IGc- S-.

Philadelphia, JB Lippinwq Go, 1993, pp 114-120,

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